Testing of welded joints in, for example, pressure vessels or tubes often leads to different types of fault indications in the weld or in material adjoining the weld. This has become accentuated by the introduction, especially in nuclear power plants, of new testing technique and new testing criteria. It is known in, for example, straight rotationally symmetrical tubes to place a compression joint over the welded joint to reinforce this and prevent crack growth in the region around the weld. For this purpose, compression joints consisting of a winding in several layers of strip or wire have been used. The strip or wire has been of memory metal. Prior to being wound on, with no significant tensile stress in the wire around the tube, at a temperature below the transition temperature of the memory metal, the wire has been stretched to a suitable length to achieve the desired compressive stress in the joint after the winding around the tube and a subsequent increase of the temperature above the transition temperature.
If the joint weld is arranged between a straight and a bent tube or between two bent tubes, however, difficulties arise in winding on a strip or a wire around the joint since the bent tube does not form a rotationally symmetrical base for the winding operation.